Process of refining oil



Nov. 3, 1942. B. CLAYTON 2,301,109

PROCESS OF REFINING OIL Filed Dec. lO, 1940 O/L HND SOAP-IN l i WHTEE /Nl l A INVENTOR. Bezyamin Clayton BY n@ ,idd tf/74.4...-

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the oil is ordinarily Patented Nov. 3, l194712 PROCESS F REFINING OILBenjamin- (nayton, Houston, Tex., assignor to Reilnin Nevada g, Inc.,Reno, Nev., a corporation of Application December 10, 1940, Serial No.369,510

12 Claims.

This invention relates to a process of refining animal and vegetableoils, and more particularly to a process of removing residual impuritiesfrom such oil after it has been treated with alkali and the resultantsoapstock separated from the oil.

In the processes of refining animal and vegetable oils by alkalitreatment, the oil, after the resultant soapstock has been separatedtherefrom either by a settling or a centrifugal separation step,contains small amounts of residual alkali, soap and water. Even in oilseparated from soapstock by means of a very eiiicient centrifugalseparation such as that effected by means of a centrifuge having a largediameter bowl and inclined discsbetween which the light effluent lsadapted to ow to render the separation more eiiective, it has been foundthat the oil thus separated may contain soap in the proportion of from300 to 1500 parts per million. It is the practice now to wash this oilin separate equipment by the use of to 20% of water and if the soapparticles left in the oil after separating the soapstock are verydiiiicult to remove, even a second washing operation may be employed.Present commercial practice favors a refined oil in which the soapstockhas been reduced to from 10-12 parts per million. Following the washingstep subjected to a vacuum drying step to remove the last traces ofwater.

It has been found that relatively small quantities of water are ample toremove large quantities of soap if the water can be brought intosumciently intimate contact with the oil in order for the water to reacha soap concentration which is in equilibrium with the concentration ofsoap remaining in the oil. It will be seen that if such a small quantityof water as 1% is added to an oil containing 1,000 parts per million ofsoap, there would be approximately ten times as much water as the soapin the oil. If all the soap were extracted in a single step theresulting soap solution would only have a soap concentration of about10%. Therefore, by eiiecting intimate con- Vtact between the oil and thewater it is possible `to remove substantial quantities of the soap bymeans of a relatively small quantity of water.

The present invention. contemplates the intro- Cil duction of a smallamount of wash water into the centrifugal bowl which is used forseparating the oil from the soapstock or into the centrifuge which isbeing used for the rst washing operation. -In either event the water isbrought into contact with the oil just after the oil has been separatedfrom either the soapstock or the wash water is introduced inside theneutral zone. 'I'he wash water thus extracts a considerable quantity ofsoap from thefseparatedkoil and then flows outwardly in the centrifugalbowl to join the heavy eilluent composed of either soapstock or Washwater. In this manner the centrifugal separation and one washing stepcan be accomplished in a single centrifuge, or two washing steps may beconducted simultaneously within a single centrifuge.

It is the principal object oi the present invention to provide a methodof washing refined oil in which small quantities of la washing liquidthe oil in a centrifuge just after the oil has been separated from a'washing liquid.

Another object of the present invention is to provide a centrifuge whichpermits the introduction of a heavy washing liquid into a light eiiiuentafter the light eiiluent has been separated from the heavyeiiiuent.

Other objects and advantages of the invention will appear in thefollowing description 0I the process and apparatus shown in theldrawing, in which Fig. 1 represents a vertical section through acentrifugal bowl which may be used to carry out the present invention.

zrepresents a fragmentary vertical section of a modiiied centrifugalbowl: and

Fig. 3 represents a fragmentaryplan section of the wash water inletpipe. y

'I'he centrifuge in Fig. l is composed of a bowl Il mounted on a shaftI2 and secured thereto'by means of nut I3. The bottom of the bowl has anupwardly extending cylindrical portion through which the shaft I2passes. A sleeve 4II having perforations IS therein is disposed aroundthe cylindrical portion Il. 'I'he bottom of this sleeve rests upon thebottom of thebowl and the top of the sleeve is adapted to support adished member I1 having an upstanding cylindrical portion Il surroundingthe sleeve II. An

water4A` as the case may be. That ia'the wash 55 general contour of thebottom of the bowl and is supported in spaced relation thereto by meansof inwardly extending flange 20. Thus, there is a passageway extendingfrom the inside of the cylindrical member I5, through the perforationsI6, between the cylindrical members I5 and I8 and between the dishedmember I1 in the bottom of the bowl. Spaced near the periphery of thedished member I1 are pipes 2l which extend upwardly from the dishedmember and are fastened thereto to provide a flow communication with thespace between the bottom of the bowl and the dished member. This pipe 2|is provided with suitable perforations 22 through which the wash watermay be discharged into the main portion of the bowl. The pipe 2I ispreferably closed at the end so that the wash water will have to passthrough holes 22 rather than directly out the end of the pipe. Thesepipes are preferably disposed inside the neutral zone of the bowl, thatis, in'

side the interface between the heavy and light effluents.

Surrounding the cylindrical portion I8 of the dished member is a tubularmember 23 which is flared out near the bottom of the bowl to provide apassageway between the dished member and the tubular member. The bottomof the tubular member 23 is disposed above the dished member to providea passage 23' beneath the tubular member. This is accomplished bysupporting the tubular member by means of ribs 24 which. rest upon theflange I9 of the dished member. The tubular member is provided with aplurality of outwardly extending ns 25 which in turn are provided withshoulders 26. A plurality of discs 21 are adapted to be slid over thetubular member and are provided with slots adapted to engage theshoulders 26 of the ribs 25, so that the discs will rotate with thetubular member. These discs may be of the conventional type employed inthis type of centrifuge, in which case they would be provided withperforations 28. By suitably constructing the dished member I1 and thewater pipe 2| the perforations in the disc may pass over and surroundthe water pipes. In this case it is preferred to have the perforations28 of sufcient size so that after the discs are disposed over the waterpipe there will still be sufcient room between the outside of the pipeand the adjacent disc to allow the passage of heavy efy fluent along theoutside of the water pipe. In this manner the advantages obtained bymeans of the perforated discs are not lost by the use of theseperforations to provide a space for the water pipe. Where theperforations in the disc are not necessary for efficient separation itis apparent that the water pipe may be of sufficient size to occupy theentire space made by the perforations. The discs 21 are provided withthe usual means of spacing so that the discs will be supported in spacedrelation with each other. Above the last discs is disposed dam member 29which has a downwardly extending flange 30 which is disposed to permitonly heavy effluent to pass beyond it. At its upper end the dam member29 has an upwardly extending flange 3| -to which is attached the lighteiiiuent discharge tube 32. This ltube has inwardly extending ribs 33which engage the annular rib 34 of the tubular member 23 to hold thetube 32 in spaced relation with .the tubular member 23, thus providing apassage for the light effluent. The discs and the dam member 29 are heldtogether by means of the spider member 35 which in turn is held inposition by the closure member 36. The lock ring 31 serves to hold theentire assembly together. A ring dam 38 supported by a shoulder on theinner surface of the closure 36 is held in position by the nut 39. Thisring dam serves to determine the neutral zone in the centrifuge and maybe replaced by another of different size when it is desired to shift theneutral zone.

The feed mechanism is composed of a central feed tube 40 supported bycover 4I. The feed tube is provided with a spiral 42 which serves tofeed the mixture to be centrifuged against the inside wall of thetubular member 23 and from there it may pass through the space betweenthe tubular member 23 and the tube I8 and outV through passage 23. 'I'hewash water inlet 43 is disposed within the feed tube a'nd passes throughthe center of the feed spiral. It extends down a considerable distanceinto the centrifuge and passes through a hole in the flange I9. The cap44 may be provided to cover the nut I3 on the end of the shaft I2.

In Fig. 2 I have illustrated a modification of the centrifuge in whichthe water pipe is disposed beyond the discs and inside the neutral zone.In this modification a support 45 between the inside of the bowl and thetop of the water pipe may be provided since in this case the discs donot surround the water pipe and accordingly the water pipe cannot besupported by them.

Fig. 3 shows a modication of the present invention in which theperforations in the discs are of an elongated shape. The short dimensionof the elongated perforation is disposed along a radius. The water pipeis brought in contact with the sides of the elongated perforation and inthis manner the discs serve to support the water pipe. The spaceprovided by the elongated perforation permits the passage of the heavyeiiluent alongside of the water pipe.

In operation the oil containing the soapstock to be separated therefromis conducted into the feed pipe 40, is forced to the periphery of thefeed pipe by` means of the spiral 42 at the end of which it isdischarged against the inner wall of the tubular member 23 and flowsdownwardly through the space between this tubular member and the tube I8and is distributed toward the periphery of the centrifuge bowl by meansof the outwardly flared portion of the tube 23. The soapstock is thrownagainst the inside of the bowl while the oil is forced inwardly to passbetween the discs 21. The wash water is introduced through the pipe 43,passes through the perforations I6, the space between the tubes I5 andIl and into the water pipe 2l from which it is distributed through theholes 22. This waterflows countercurrent to the inward flow of the oiland effects intimate contact with the oil, thus removing a substantialportion of the soapstock and other impurities from` the oil. Some of thewash water containing the soapstock and the impurities may dischargethrough the perforations 28 and the discs and thus take a short path tothe heavy eilluent discharge. Other portions of the wash water passoutwardly between the discs and join the main portion of the soapstockwhich is withdrawn at the heavy effluent discharge. T he oil afterpassing the stream 0f wash water iiows inwardly along the surface of thediscs and is discharged into the space between the ribs 25 and fromthere it flows upwardly through the space between the tubes 32 and 23and is discharged through the light effluent discharge.

The heavy effluent along the inner wall of the bowl passes around theflange 30 of dam member 29, up through the space 'between members 29 and36, over the ring dam 3l and out the heavy efiluent discharge.

It will be apparent that by means of the present process a singlecentrifuge may be used to effect the primary separation of impuritiesfrom the oil as well as to effect a substantial washing of the separatedoil.

The washing accomplished by this small amount of water either makes aseparate washing unnecessary or, in the case of oil from the primaryseparation containing an excessive amount of light floating soap, onlyone separate operation may be required.`

The present process may also be employedto effect a double washingwithin a single centrifuge. v

Thus, a refined oil from which the majority of the soapstock has beenseparated but which contains from 300 to 1500 parts per million of soapcan be admixed with a considerable quantity of water, which mixture canbe separated in the present centrifuge. This washing will remove up to95% of the residual soapstock and by the use of additional wash waterdischarged into the separated washed oil it is possible to reduce the`than 1% may be found satisfactory in particular instances.

In the treament of certain oils it may be desirable to heat the materialin the centrifuge. Thisv may be done in the manner disclosed in myPatent No. 2,100,277. Likewise, heat may be added by the use of hotwater, even above its atmospheric boiling point if pressure is employed.

The present process is not limited to the removal of residual soapstockfrom a refined oil but may also be employed to wash any impurities fromthe oil after it has been subjected to any kind of refining treatment.For example, where the oil is subjected to a degumming treatment thepresent process may be employed to remove traces of gums and otherimpurities which have precipitated but which have remained with the oiland have not been separatedin-the primary separation. Likewise, it canbe employed to remove residual traces of impurities as well as acid froman oil which has been subjected to acid refining.

Similarly, the present process while preferably employed in conjunctionwith the continuous reiining of oil, such as according to U. S. PatentNo. 2,100,274, is not limited to continuous rening but may also beemployed to remove residual impurities from oil refined according to thebatch process.

The various modifications of the process of the present invention areapplicable to vegetable and animal oils in general. Such vegetable oilsas cottonseed oil, com oil, soya bean oil, linseed oil, sesame oil, etc.are within the contemplation of the invention. The term "animal oils isalso intended to include fish oils, such as sardine, menhaden, orherring oils. By the employment of the terms oils or oil in the claims Iintend to embrace glyceride fats or oils, irrespective of the viscositythereof.

l While the description of the present invention has been particularlydirected to the-use of the type of centrifuge illustrated, it will beapparent 75 that other types of centrifuge may be modified to performthe present invention.

It is apparent that other washing iiquids besides water may be used ifdesired. For example, various electrolytes may be employed particularlywhere the process is employed for the removal of gums and phosphatides.Likewise, in certain instances, soap solvents such as alcohols which areimmiscible with the oil may be employed, either alone or in arlmixture`with other liquids such as water. Y

While various modifications have been disclosed` the invention is not tobe limited thereto but it is to be understood that it may be variedwithin the scope of the appended claims.

What I claim is:

l. The process of separatingy impurities from glyceride oil whichcomprises subjecting said oil containing impurities to centrifugalseparation in a centrifuge to remove a' portion of the impuritiestherefrom, washing the resultant separated oil by introducing arelatively small quantity of washing'liquid into said separated oilwithin said centrifuge immediately following separation.

2. 'I'he process'of separating impurities from glyceride oil whichcomprises subjecting said oil containing impurities to centrifugalseparation ina centrifuge to remove a portion of the impuritiestherefrom, and washing the resultant separated oil by introducing arelatively small quantity of washing liquid into the separated oilinside the neutral zone of said centrifuge while said separation isbeing affected therein.

3.k The process of separating impurities from glyceride oil whichcomprises subjecting said oil containing impurities to centrifugalseparation in a centrifuge to remove a portion of the impuritiestherefrom, introducing a relatively small quantity of. a washing liquidinto the resultant separated oil while said oil is still within saidcentrifuge, and removing the washing liquid along with the previouslyseparated impurities.

- 4. The process of separating soapstock from glyceride oil whichcomprises subjecting said oil containing soapstock to centrifugalseparation in a centrifuge to remove a portion of the soapstocktherefrom, introducing into the resultant separated oil while in saidcentrifuge a relatively small quantity of a washing liquid, andseparating the washing liquid from the oil.

5. The process of separating soapstock from glyceride oil whichcomprises subjecting said oil containing soapstock to centrifugalseparation in a centrifuge to remove a portion of the soapstocktherefrom, introducing into the resultantseparated oil while in saidcentrifuge a relatively small quantity of water, and separating waterfrom the oil.

6. The process of separating impurities from glyceride oil whichcomprises subjecting said oil containing impurities to centrifugalseparation to remove a portion of the impurities therefrom, admixing theresultant separated oil with a quantity of washing liquid and subjectingthe mixture to centrifugal separation, introducing into the resultantwashed oil while in the centrifuge used for said last mentionedseparation and immediately following separation from the washing liquida relatively small quantity of washing liquid, and separating thewashing liquId from the oil.

'1. The process of separating 50895150011 from glyceride oil whichcomprises separating the maior portion of the soaDStOCk from the ou admixing une separated ou with a quantity of Washing liquid, subjectingthe mixture to centrifugal separation in a centrifuge to remove aportion of the washing liquid and residual soapstock therefrom,introducing into the resultant separated oil while in said centrifuge arelatively small quantity of washing liquid, and separating the washingliquid from the oil.

8. The method of refining glyceride oil which comprises treating the oilwith an alkaline refining agent, separating the major portion of theresultant soapstock therefrom, admixing the resultant separated oil witha quantity of washing liquid, subjecting the mixture to centrifugalsepa-- ration in a centrifuge, and introducing into the separated oilwhile in said centrifuge a relatively small quantity of washing liquidto remove residual impurities from the oil.

9. The process of separating soapstock from glyceride oil whichcomprises subjecting a mixture of oil and washing liquid to centrifugalseparation in a centrifuge to remove a portion of the residual soapstocktherefrom, introducing into the resultant separated oil while in saidcentrifuge a relatively small quantity of washing liquid, and removingthe washing liquid from the oil.

10. The process of separating impurities from glyceride oil whichcomprises subjecting said oil containing impurities to centrifugalseparation in a centrifuge to remove a portion of the impuritiestherefrom, introducing a relatively small quantity of a washing liquidinto the resultant separated oil within said centrifuge, removing thewashing liquid along with the previously separated impurities andheating the bowl of the centrifuge during said separation to arelatively high temperature so as to lower the viscosity of the oil.

11. 'Ihe process of separating impurities from a glyceride oil whichcomprises introducing an cil containing impurities into a centrifuge,forming a layer of impurities and a layer of separated oil, said layersbeing separated by a neutral zone,in troducing into said separated oillayer a small quantity of a washing liquid, forcing said washing liquidthrough at least a portion of said separated oil, through said neutralzone and into said layer of impurities, and separately removingimpurities and oil from said centrifuge.

12. The process of separating impurities from a glyceride oil, whichcomprises, subjecting said oil containing said impurities to centrifugalforce in a centrifuge to separate said 'impurities from said oil,introducing a washing liquid into said oil while the same is stillpassing through said centrifuge and after a portion of said impuritieshas been separated from said oil, and separating washing liquid fromsaid oil in said centrifuge to remove additional impurities therefrom.

BENJAMIN CLAYTON.

